1. Field of the Invention
The present invention relates to a manipulator for actuating a working unit by operating an operating unit.
2. Description of the Related Art
Heretofore, there has been used in the art an integral medical manipulator having an end working unit and a hand-operating unit which are connected to each other by a connector. Under endoscopic observation, the hand-operating unit is held by hand and operated to insert the end working unit into a body cavity and then actuate the end working unit to perform various medical treatments on the living body tissue.
Japanese Laid-Open Patent Publication No. 2003-61969 discloses a manipulator having an operating unit and a working unit which incorporates in the operating unit a pair of grippers for gripping a living body tissue. The grippers can be opened and closed about a gripper shaft, and can be angularly movable in unison about a pitch axis and a roll axis. A wire is trained around the output shaft of a motor housed in the operating unit and a pulley housed in the working unit through a connector. The torque that is required to operate the working unit is transmitted from the motor through the wire to the pulley, and then from the pulley to gears.
A manipulator disclosed in Japanese Laid-Open Patent Publication No. 2002-102248 is similar in structure to the manipulator disclosed in Japanese Laid-Open Patent Publication No. 2003-61969, and further includes a power boosting mechanism disposed in the working unit for increasing the gripping forces of the grippers.
With the manipulator disclosed in Japanese Laid-Open Patent Publication No. 2003-61969, it is difficult to increase the gripping forces of the grippers. For example, if the output torque of the motor is simply increased to increase the gripping forces, then the expansion and contraction properties and tensile strength of the wire, and the mechanical strength of the torque transmitting mechanism have to be increased. However, these efforts make it difficult to reduce the diameter of the connector. In addition, since various components for achieving movements about the respective axes need to be installed in the working unit which is of a small size, they pose a spatial limitation on attempts to increase the speed reduction ratio in the working unit.
Although the gripping forces of the grippers are increased by the power boosting mechanism in the manipulator disclosed in Japanese Laid-Open Patent Publication No. 2002-102248, the grippers are offset with respect to each other when they grip a living body tissue. Therefore, the operator is required to operate the manipulator while at the same time predicting a vertical offset action of the grippers. For this reason, there have been demands from manipulator operators (e.g., surgeons) for a manipulator that can be operated neatly and smoothly without the need for a burden in predicting the offset action.